Results
The proportion of individuals which survived till the end of the
reproduction period in the GTI treatment declined with the increasing
temperature (Fig. 1), and the decline was significant when compared to
control treatment (Treatment * Generation est. ± s.e. = -1.004 + 0.228,
z = -4.393, p < 0.001; Table S1). Within GTI populations, the
survival was affected by the interaction between population type (FT vs.
ST) and generation (est. ± s.e. = 0.538 + 0.184, z = 2.992, p = 0.003;
Fig. 1, Table 1). Strikingly, among populations subjected to temperature
stress, very few adults survived in FT populations at generation four
(Fig. 1) and consequently, nine (75%) of these populations went extinct
(Fig. 2). At the same time, only one (8,3%) ST population went extinct,
a significantly lower proportion compared to FT populations (est. ± s.e.
= 3.724 + 1.741, z = 2.139, p = 0.032). Interestingly, extinction
proceeded despite that expression of fighter morphs in FT populations
declined from 76% at first generation to 25% at fourth generation
(est. ± s.e. = -1.598 + 0.218, z = -7.327, p < 0.001; Fig. S2,
Table S2). Indeed, the reason for higher extinction of FT did not seem
to have been associated with higher male mortality in FT populations, as
indicated by the non-significant effect of population type*sex
interaction on proportion of surviving adults across four generation
(full model: est. ± s.e. = 0.154 + 0.301, z = 0.511, p = 0.609).
However, there was a significant generation * sex interaction (best
model: est. ± s.e. = 0.462 + 0.145, z = 3.184, p < 0.001 Fig.
S3; Table S3): in both F and S populations, females survived better than
males in early generations, but then in following generations, as
temperature increased and survival decreased, the differences between
sexes decreased.